If you've read my curriculum link above, you already know that we'll be using Right Start Levels B and E this year. I am really excited about the Right Start program for both my guys. I dove into it a little bit this summer and used many of the activities during some remedial and enrichment tutoring that I did. I really like the emphasis on teaching beginning number concepts in combinations of 5 and 10 as well as the way the program uses games to reinforce the concepts. It is very hands-on, and without having actually used it with my sons, I already feel that I can say it was well worth the price.
Another great book that I used during tutoring this summer is Mega-Fun Math Games: 70 Quick-and-Easy Games to Build Math Skills by Dr. Michael Schiro. I picked this up at a used curriculum sale this summer and it has lots of really great math games to reinforce learning for children in grades 2-5. I am very excited to play these games with my oldest son this year. If you have a middle to upper grades child, I really recommend this resource.